Telephone-switch



(No Modei.)

H. R. MILLER.

Telephone Switch;

No. 237,577. Patented Feb. 8,1881.

LINE 4 l/VE N. PETERS, PHOTO-LITHDGRAPHER, WASHXNGTON. u n.

UNinn STATES FFTQEC PATENT TELEPHONE-SWITCH.

SPECIFICATION forming part of Letters Patent No. 237,577, dated February 8, 1881. Application filed September 24, 1880. (No model.)

To all whom it may concern V Be it known that I, HOMER R. MILLER, of Framingham, in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvementin Telephone-Switches; and I do herebydeclare that the following is a full, clear, and exact description of the same.

My invention relates to telephones; and it consists of lockin g mechanism whereby the operator at any given station may look out all the other telephones in a line excepting his own and that of the station with which he desires to communicate.

Heretofore mechanisms have been devised for shunting out stations in the line on one side of any given station, leaving it possible to include in the circuit any of the others between the operator and the called station. Means have also been devised for cutting out at the central station, or at any given station, the telephone-alarms of all the other stations.

The object of my invention is the complete exclusiomby simple and efficient Ineans,ot' all other stations in the line, excepting those between which the communication is held.

The accompanying drawing illustrates the best method of carrying my invention into effeet.

The shunting mechanisms are represented as inolosed in a box, which may serve as a base for any suitable signaling apparatus.

The main-line wires are connected to ordinary posts on the box or case A at a I), and the wire' from a extends to the helix of a small electro-magnet, c, situated in the upper part of the case. From the other end of the helix the wire 1 extends to the point 2, where it connects with the wire of the telephone. At the point 3, however, it is in connection with a spring-point, d, fixed to the board partition M, or otherwise insulated on the case, against which, as shown in the figure, rests a metallic switch-lever, e, insulated on a pivot, f. This lever carries an insulating-block, g, to which is attached a pron ged plate, '5. From the pivoted end of the lever e connection is made directly to the other end, I), of the main line by means of the wire 4, and when the lever e is in contact with the point 61 the circuit is through the parts just described. At a suitable distance above the lever 6 when in the position shown,

resting on stop a, is a point, It, similar to 01, connected by wire 5 to insulated post 6. The remainder of the circuit consists of the wire 7,

connected to post 6, said wire passing through theinduction-coil in the transmitter G, and continuin g by wire 8 to post g, and thence through the telephone to its connection with the part already described at post 2. This circuit is completed by the upward movement of the switch-lever c, causing it to leave the point (I and press upon the inclined spring end of point h. The same movement. of this lever moves also the pronged plate 6. These prongs are bent at the ends, and when the lever is down, as shown in the figure, the ends bear only on the point 7; on partition M; but when the lever e is raised the prongs are moved so that one hears upon the point and the other on a similar point, Z, forming electrical connection between them. The point In is connected to the post 10 by wire 11, and thence to one pole of the transmitter-battery I). The wire from the other pole passes through the induction-coil in the transmitter, and thence to the post 6, and reaches the point l through the wire 12. I

It will be apparent from the description given that the circuit of the transmitter-battery is made or broken by the movement of the prongs, caused by the movement of the switch-lever e, which action, as is well understood, is necessary when the ordinary Le Glanohe or a like battery isused with the transmitter.

It will be observed that the free end of the lever 6 extends through a slot (indicated in dotted lines) in a vertical rod, E. This rod has a hook, it, on the lower end, on which is hung the telephone B, and passes through guides o 0, fixed to the frame. It is supported upon a spring, 19, which rests on the upper guide-piece 0, and bears underneath a pin in the end of the rod. The slot in the rod E is wider than the switch-bar, and allows the spring 19 to lift the rod slightly without moving the lever. The tension of the spring is such that the weight of the telephone B will depress the rod so as to bring the notch g in said rod opposite the end of a bent lever, s, the end of which is fitted to engage with the IOC notch and lock the rod, so that it cannot be pushed up. The armature of the magnet c is attached to the upper end of the bent lever s, the lever being so pivoted upon an arm in the case that the armature, when drawn up, shall throw the lower end of the lever out of connection with the notch, but when not drawn up the armature shall fall back by gravity and throw the end of 8 into connection and lock the rod, so that it cannot be raised. It will be understood from this description of the parts that the magnet c at every station in the line is in the main-line circuit.

Under ordinary conditions of the circuit, and when no telephones are switched in, the effect of the current is sufficient to keep the armature t drawn up and the rod unlocked; but when an operator at any given station is called he unhooks and shunts in his telephone. The greatresistance of the telephone then brought into the line so weakens the current that it will no longer act upon the electro-nmgnet o sufficiently to draw up the armature, and these armatures in the whole circuit of the line will therefore fall back by their own gravity and lock all the rods through which the shunting devices are operated, excepting that from which the telephone has been removed. This happens, of course, at the station which has been called, where, the operator having removed the telephone, the rod E is lifted by the spring p sufficiently to raise the notch above the catch without disturbing the shunting-lever c, as that moves in the slot. The operator at this station may therefore push up the rod E and shunt in his telephone, and is thus able to communicate with another station without liability of interruption by the operator at any other station, or that the communication will be heard except at the two stations in connection.

The operation of the shunting devices is apparent from the description heretofore given of these devices. By pushing up the rod E the shunting-lever c is lifted so that it leaves the point (1 and is moved upon the point h, on which it is held by friction. At the same time the points of the plate i are shifted so as to include the pointsl and 7, This movement of the lever E from d to h shunts in the telephone, and that of the points of plate 1' closes the circuit of the local battery.

A modification of the locking devices may be made by dispensing with the electro-magnet 0, and extending the lever 8 up between the arms of the main magnet of the signaling apparatus. In that case the lever should be so pivoted thatit will vibrate from side to side between the arms, and must be itself a permanent magnet and incline by gravity to the like pole of the main magnet. The locking end may be so arranged that it will engage with the notch by the inclination caused by gravity. When the main electro-ma-gnct is charged the end of the lever will be repelled from that pole to which it was inclined by gravity, and then will the rod be unlocked; but at all other times the rod andshunting apparatus moved thereby will be locked. As the locking depends upon the weakening of the main-line current, it is plain that the locking mechanism is acted upon by the key as effectually as by the shunting in of any of the telephones of the line. If it should be deemed desirable, therefore, as maysometimes happen at the central office, to look all the telephones of the line, it may be done by throwing open the key.

Having thus described my invention. what I claim as new, and desire to secure by Letters Patent, is-

1. In combination with the shunting mechanisms of a series of telephones in a circuit, looking mechanisms. substantially as described, and electro-magnets, said locking mechanisms being operated through the magnets by the weakening of the current when any telephone is shunted in, substantially as set forth.

2. In combination with the shunting mechanisms of the series of telephones of a circuit, locking-levers and electro'magnets in the main line operating to hold said levers in unlocking position only when no telephone is in thecircuit, said locking-levers being combined, also, with mechanisms, substantially as described, whereby the unhooking of any one of the telephone'receivers prevents the station of that instrument from being locked out, as set forth.

3. The combination, with an elcctro-magnet situated in the main line of a series of telephones, of the levers and notched rod E, provided with book atits lower end and with spring at the upper, said lever being connected to the shunting devices, substantially as described.

4. The combination, with the lever c. locking devices, and rod E, of the points 61 and h and connecting wires, substantially as described.

5. The combination, with the lover a, rod E, and locking devices, ofinsnlated pron ged plate i, points It and 1., and battery-connections, substantially as described.

In testimony whereofI have signed my name to this specification in the presence of two subscribing witnesses.

HOMER It. MILLER.

Witnesses:

H. B. MoUL'roN, F. L. MIDDLETON. 

